The present invention is related to gas turbine engines, and in particular to vane shroud rail pockets for feather seals. Gas turbine engines operate by combusting fuel in compressed air to create heated gases with increased pressure and density. The heated gases are ultimately forced through an exhaust nozzle, which is used to step up the velocity of the exiting gases and in-turn produce thrust for driving an aircraft. In turbofan engines the heated gases are used to drive a turbine for rotating a fan to produce thrust, and to drive a turbine for driving a compressor that provides the compressed air used during combustion. Compressors and turbines are comprised of alternating stages of stator vanes and rotor blades that are arranged radially around a center axis to form an axial air and gas flow path. In the compressor, for example, rotating blades push air past the stationary vanes at each stage to increase the pressure and density of the air. The stator vanes convert the kinetic energy of the air into pressure, and they redirect the trajectory of the air coming off the rotors for flow into the next compressor stage. Gas turbine efficiency is closely linked to the ability of a gas turbine engine to direct airflow through each rotor/stator stage efficiently and without leakage. As such, various air seals are used throughout the engine to, among other things, maintain airflow and pressure balances.
It is particularly advantageous to seal the outer and inner diameter ends or the rotor blade and stator vane stages. The blades are fixed at their inner end to rotating rotors connected to a turbine shaft, and the vanes are suspended from engine casings between the rotating blades. In order to facilitate engine disassembly and repairs, each vane stage is typically comprised of a plurality of vanes or vane segments, thus necessitating a seal between adjacent vanes at each stage as this interface provides a point for potential leakage of airflow from the flow path. Accordingly, each vane typically includes inner and outer diameter vane shrouds (or platforms) that abut vane shrouds of an adjacent vane. A feather seal is typically provided between adjacent vane shrouds to assist in sealing the flow path. In order to accommodate changing engine conditions, the feather seal is not directly secured to the vane shroud, but is maintained relatively stationary between feather seal rails of adjacent vane shrouds. In order to secure the feather seal, the rails must be of a significant thickness and must be machined to precise dimensions. Thus, typical feather seal rails add significant weight and complexity to each vane shroud. There is, therefore, a need for improved vane shrouds that are lighter and more easily manufactured.